The present invention concerns a process for treating kernels with a shell-like wall, in particular nuts such as for example cashew nuts, macadamia nuts, coconuts or the like, which are supplied by way of transport means and which are held between two conveyor belts, wherein at least one groove is milled into the shell-like wall or the shell of the nut by a milling means in the form of milling discs which are arranged rotatably about an axis of rotation and which engage into the space between the conveyor belts, which groove facilitates breaking open the shell of the nut by a breaking means or splitting means, and apparatus for carrying out the process.
As nuts have been known as foodstuff since the earliest times, many different ways of opening nuts have been sought. Difficulties arise in this respect inter alia by virtue of the different configurations of the nut shells.
Cashew nuts comprise for examle very hard thick-walled shells which contain kidney-shaped irregular kernels which are each formed from two halves which cling lightly together, similarly to peanuts or ground-nuts. These kernels have a high market value, and undamaged whole kernels produce approximately twice the clear return of broken kernels.
In order to obtain the kernels, the tough cashew shell which is also kidney-shaped, like the configuration of the kernels, must be broken. This is still predominantly a manual operation, after special preliminary treatment, but attempts have been made to provide for opening of the shells by mechanical means such as for example by cutting the shells open, although with little success, that is to say, resulting in a small proportion of whole kernels.
For the purposes of opening walnuts, use is made for example of a milling device which has two milling discs which are mounted on movable pivotal arms and between which the walnuts are guided in a loose arrangement by means of conveyor belts. The conveyor belts carry chamber-like subdivisions in which the nuts are disposed. As however the absence of damage to the kernels is not an important point in regard to walnuts, the milling discs engage to any depth into the nut.
This apparatus cannot be used for opening for example cashew nuts, as it is precisely the absence of damage to the kernels which is the most important factor.
The operation of breaking open the shells is also effected in a so-called palm-nut breaker in which the nuts are flung against the wall. In this case also the amount of broken nuts is very high.
A manual operation of breaking open the nuts results in a high level of cost and a large work force. In addition the oil which is present for example in the cashew nut shell endangers the health of the workers.
Further difficulties occur when transporting the nuts to the opening means.
Hitherto, the transport means used were simple transport belts which, although suitable for the manual operation of opening the nuts, do not take any account whatever of the possibility of automation, as the nuts are of widely differing shapes.
However, it is precisely automation of transportation and breaking open of the nuts which appears to be urgently necessary as the nuts are ever increasing in value as foodstuffs and in future are also to be grown on an enlarged scale in plantations.
The problem of the present invention is to develop an apparatus for processing nuts, which, in spite of the most extensive automation, leaves the kernels undamaged in the operation of opening the nuts and which nonetheless operates economically. In addition, the apparatus should be easy to operate and to maintain, as the intention is for the apparatus to be used as close as possible to the area in which the nuts are grown, that is to say, for example, in regions which are of poor development from the infrastructure point of view.